For a number of years there has been increasing use and popularity of skateboards incorporating wheels mounted at opposite ends of transverse truck mechanisms secured to forward and rear end portions of an elongated foot engaging platform. The truck mechanisms have transverse axle portions with anularly disposed projections for securing the same to a mounting plate.
One of such projections has a ball-socket engagement with the mounting plate, and the other projection is secured to a compression element on a spaced portion of the mounting plate, with the point of attachment to said compression element being spaced from the mounting plate substantially further than the ball-socket.
This means for securing the axle portion to the mounting plate permits limited movement of the axle portion about an axis which is angularly disposed with respect to the mounting plate and platform, providing movement which can be viewed as a combination of coplanar rotation and tilting of the axle portion with respect to the platform as weight is shifted from one side to the other of the platform. The extent of such combined rotational and tilting movement can be increased or decreased by respectively loosening or tightening said compression element.
By mounting the trucks in opposite directions with the ball-socket portions thereof toward the ends of the platform, weight changes on the platform cause the axle portions of the trucks to rotate in opposite directions to thereby permit steering of the skateboard in operation by shifting of the weight from side to side on the platform, with the skateboard turning in the direction of the side to which weight is applied.
In addition to this type of steering, the sensitivity of which can be varied by adjustment of the compression elements, quick steering or change of direction can be accomplished by momentarily raising one truck and its associated wheels; and this type of manipulation is frequently facilitated by providing upwardly inclined contour to the rear end of the skateboard platform.
With the growing popularity of roller skateboards, it is not surprising that others have attempted to adapt the skateboard principle to ice skateboards. A problem arises, however, in that the steering control above described, which works effectively for roller skateboards, does not appear to be as effective when ice blades are substituted for the conventional wheels.
A preliminary search has brought to light the following recently issued United States patents relating to ice skateboards:
______________________________________ Paul Mogannam 4,043,565 August 23, 1977 William K. Newell 4,114,913 Sept. 19, 1978 Thomas L. Mayes 4,521,029 June 4, 1985 Adam A. Shumayes et al 4,896,893 January 30, 1990 ______________________________________
None of these patents in any way suggest the improvement of the present invention, but two of the patents reflect awareness of the problem of attaining the desired steering control with ice blades.
U.S. Pat. No. 4,043,565 provides blades of generally triangular contour, with each edge ground in a concave fashion to provide better ice gripping to enhance steering control. As the pre-adjusted edges become worn through use, causing diminishing steering control, the triangular blades can be rotated to expose freshly ground edges to thereby, for a time, improve the steering control.
In U.S. Pat. No. 4,114,913 an effort is made to enhance steering control by specially contouring the ice engaging blade edge, as indicated for example, by the protruding V-shaped contour of the blade edge, as shown in FIG. 3 of the patent. This approach, while possibly effective with a freshly sharpened blade, would rapidly lose its effectiveness by wearing down of the ice engaging edge of the V-contour in use.
It would appear therefore that the efforts of others have failed to provide an ice skateboard which can afford the operator sustained steering control.